diff --git a/debian/snapshot.go b/debian/snapshot.go
index 70724e5f..89623089 100644
--- a/debian/snapshot.go
+++ b/debian/snapshot.go
@@ -3,6 +3,7 @@ package debian
 import (
 	"bytes"
 	"code.google.com/p/go-uuid/uuid"
+	"errors"
 	"fmt"
 	"github.com/smira/aptly/database"
 	"github.com/ugorji/go/codec"
@@ -29,9 +30,9 @@ type Snapshot struct {
 }
 
 // NewSnapshotFromRepository creates snapshot from current state of repository
-func NewSnapshotFromRepository(name string, repo *RemoteRepo) *Snapshot {
+func NewSnapshotFromRepository(name string, repo *RemoteRepo) (*Snapshot, error) {
 	if repo.packageRefs == nil {
-		panic("repo.packageRefs == nil")
+		return nil, errors.New("mirror not updated")
 	}
 
 	return &Snapshot{
@@ -42,7 +43,7 @@ func NewSnapshotFromRepository(name string, repo *RemoteRepo) *Snapshot {
 		SourceIDs:   []string{repo.UUID},
 		Description: fmt.Sprintf("Snapshot from mirror %s", repo),
 		packageRefs: repo.packageRefs,
-	}
+	}, nil
 }
 
 // String returns string representation of snapshot
diff --git a/debian/snapshot_test.go b/debian/snapshot_test.go
index c34487c1..5a073ad1 100644
--- a/debian/snapshot_test.go
+++ b/debian/snapshot_test.go
@@ -19,29 +19,30 @@ func (s *SnapshotSuite) SetUpTest(c *C) {
 }
 
 func (s *SnapshotSuite) TestNewSnapshotFromRepository(c *C) {
-	snapshot := NewSnapshotFromRepository("snap1", s.repo)
+	snapshot, _ := NewSnapshotFromRepository("snap1", s.repo)
 	c.Check(snapshot.Name, Equals, "snap1")
 	c.Check(snapshot.NumPackages(), Equals, 3)
 
 	s.repo.packageRefs = nil
-	c.Check(func() { NewSnapshotFromRepository("snap2", s.repo) }, PanicMatches, "repo.packageRefs == nil")
+	_, err := NewSnapshotFromRepository("snap2", s.repo)
+	c.Check(err, ErrorMatches, ".*not updated")
 }
 
 func (s *SnapshotSuite) TestKey(c *C) {
-	snapshot := NewSnapshotFromRepository("snap1", s.repo)
+	snapshot, _ := NewSnapshotFromRepository("snap1", s.repo)
 	c.Assert(len(snapshot.Key()), Equals, 37)
 	c.Assert(snapshot.Key()[0], Equals, byte('S'))
 }
 
 func (s *SnapshotSuite) TestRefKey(c *C) {
-	snapshot := NewSnapshotFromRepository("snap1", s.repo)
+	snapshot, _ := NewSnapshotFromRepository("snap1", s.repo)
 	c.Assert(len(snapshot.RefKey()), Equals, 37)
 	c.Assert(snapshot.RefKey()[0], Equals, byte('E'))
 	c.Assert(snapshot.RefKey()[1:], DeepEquals, snapshot.Key()[1:])
 }
 
 func (s *SnapshotSuite) TestEncodeDecode(c *C) {
-	snapshot := NewSnapshotFromRepository("snap1", s.repo)
+	snapshot, _ := NewSnapshotFromRepository("snap1", s.repo)
 	s.repo.packageRefs = s.reflist
 
 	snapshot2 := &Snapshot{}
@@ -67,11 +68,11 @@ func (s *SnapshotCollectionSuite) SetUpTest(c *C) {
 
 	s.repo1, _ = NewRemoteRepo("yandex", "http://mirror.yandex.ru/debian/", "squeeze", []string{"main"}, []string{})
 	s.repo1.packageRefs = s.reflist
-	s.snapshot1 = NewSnapshotFromRepository("snap1", s.repo1)
+	s.snapshot1, _ = NewSnapshotFromRepository("snap1", s.repo1)
 
 	s.repo2, _ = NewRemoteRepo("android", "http://mirror.yandex.ru/debian/", "lenny", []string{"main"}, []string{})
 	s.repo2.packageRefs = s.reflist
-	s.snapshot2 = NewSnapshotFromRepository("snap2", s.repo2)
+	s.snapshot2, _ = NewSnapshotFromRepository("snap2", s.repo2)
 }
 
 func (s *SnapshotCollectionSuite) TearDownTest(c *C) {